WASHINGTON (CNN) -- The looming Senate showdown over filibustered judicial nominees has been averted by a bipartisan agreement that gives both sides some -- but not all -- of what they wanted.

The agreement, announced late Monday, came after days of talks among a group of centrist senators.

The crisis had prompted bitter debate over partisan power that could have permanently changed the rules, and perhaps the character, of the Senate.

Under the agreement, three of President Bush's nominees for appellate courts stalled by Democratic filibusters will go forward and two others will remain subject to filibuster.

The group's members also agreed that they would oppose attempts to filibuster future judicial nominees except under "extraordinary circumstances."

What would constitute "extraordinary circumstances" was not defined.

Fourteen senators -- seven Democrats and seven Republicans -- signed on to the deal.

That bloc is large enough to derail both Democratic filibusters of judicial nominees and any GOP attempt to employ the so-called "nuclear option" to change Senate rules through procedural maneuvers to prevent the tactic from being used.

The deal came a day before Senate Majority Leader Bill Frist was expected to invoke the option to preclude a Democratic filibuster blocking the nomination of federal appeals court nominee Priscilla Owen.

Under the deal, the senators will allow three of Bush's controversial nominees to come to a vote: Owen, Janice Rogers Brown and William Pryor.

The group made no commitment to vote for or against a filibuster on two nominees, William Myers and Henry Saad.

Senate Minority Leader Harry Reid later welcomed the deal and indicated Democrats would continue to filibuster Myers and Saad, likely dooming their nominations.

"This is really good news for every American," the Nevada Democrat told reporters. "Checks and balances have been protected."

Reid said the agreement sent President Bush, Vice President Cheney and what he called the "radical arm of the Republican base" the "undeniable" message that "abuse of power will not be tolerated."

Frist was less enthusiastic, saying the agreement "falls short" of the principle that all judicial nominees should receive a vote on the Senate floor.

But he said he was "very pleased" the nominations of three Bush appointees will finally come to a vote.

"It has some good news, and it has some disappointing news, and it will require careful monitoring," Frist said.

Across town, White House counsel Harriet Meirs briefed Bush on the details of the deal, which the White House called a "positive development."

"Nominees that have been waiting for a long time for an up or down vote are now going to get one. That's progress," White House press secretary Scott McClellan told CNN.

"We will continue working to push for an up-or-down vote on all our nominees."

In announcing the deal, Republican Sen. John McCain of Arizona singled out a senator from each party for their "vital" roles in the negotiations: Republican John Warner of Virginia and Democrat Robert Byrd of West Virginia.

Warner said he was led to compromise because of one unanswered question that guided him through the process: "What would happen to this Senate if the nuclear option were done?"

"No one was able to answer that to my satisfaction," he said.

Byrd, the chamber's most senior lawmaker, applauded the group of 14.

"We have lifted ourselves above politics, and we have signed this document in the interests of the United States Senate, in the interest of freedom of speech, freedom of debate and freedom to dissent in the United States Senate," Byrd said.

"Thank God for this moment and for these colleagues of mine."

McCain said the senators agreed that filibusters would only be used under "extraordinary circumstances" and that they would "try to do everything in our power to prevent filibusters in the future."

He applauded Warner and Byrd for bringing both sides together to forge an agreement based on Senate principles: "trust, respect and a mutual desire to see the institution of the Senate function in ways that protect the rights of the minority."

"We have reached an agreement to try to avert a crisis in the United States Senate and pull the institution back from a precipice that would have had -- in the view of all 14 of us -- lasting impact, damaging impact on the institution," McCain said.

Vote set for Tuesday

Democrats filibustered 10 of Bush's 218 nominees in his first term, saying they were too radical for a lifetime appointment to the bench.

Forty-four Democrats and one independent in the current Senate have stuck to that position.

Bush renominated seven of the judges -- including Owen, a Texas Supreme Court justice, whose nomination to the 5th U.S. Circuit Court of Appeals the Senate began debating last week.

Frist said Monday he expected the nominees not specifically covered by the bipartisan compromise would get a vote on the Senate floor.

With 55 seats, Republicans have been unable to garner the 60 votes that Senate rules specify are necessary to end a filibuster -- a form of extended debate that has been part of Senate rules since the early 19th century.

Frist thus had put into motion what some call the "nuclear option."

Sen. John Cornyn, a Texas Republican, moved Friday for cloture to end debate on Owen's nomination. The vote was set for Tuesday. (Full story)

If the cloture vote were to fail, Frist would use some parliamentary maneuvering -- with help from Cheney as the body's presiding officer -- to get a vote on a procedural motion to limit debate, according to a scenario cited in The Washington Post.

Such a vote, assuming Frist was successful, would set a precedent by cutting off debate with a simple majority of 51, instead of the three-fifths supermajority required for cloture on a filibuster.

The "nuclear" aspect of the scenario is that it would effectively circumvent a Senate rule that requires a two-thirds vote of 67 to change a rule.

If the Republican majority eliminated the filibuster, Democrats threatened to use Senate rules to push their agenda and disrupt the GOP's -- effectively slowing the chamber's business to a crawl.

Earlier Monday, Bush called for the full Senate to vote on his judicial picks, saying his nominees deserve "a fair hearing."

"I expect them to get an up-or-down vote," Bush said at a news conference. "And I think the American people expect that as well."

The nominees under consideration have been tapped for federal appellate courts. But Supreme Court nominations -- including the chief justice post -- are likely at stake down the road.